Hypoglossal Nerve — MFDS Part 1 MCQ

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EasyAnatomy (Head & Neck)Hypoglossal NerveMFDS Part 1

Following surgery in the upper neck, a patient has wasting and fasciculation of the left side of the tongue. When the tongue is protruded, it deviates to the left. Which nerve is most likely to have been damaged?

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Correct answer: E — Hypoglossal nerve (XII)

The correct answer is E, the hypoglossal nerve (XII). It provides motor innervation to the intrinsic and most extrinsic muscles of the tongue. A unilateral lower motor neurone lesion causes ipsilateral weakness, wasting and fasciculation. On protrusion, the intact contralateral genioglossus pushes the tongue towards the weak, affected side. The lingual nerve carries general sensation from the anterior two-thirds of the tongue but does not supply its muscles. The facial nerve carries taste fibres from this region through the chorda tympani. The glossopharyngeal nerve supplies sensation and taste to the posterior third, while vagal injury more typically produces palatal, pharyngeal or laryngeal dysfunction rather than unilateral tongue wasting.

Reference: Warwick Medical School and University Hospitals Coventry and Warwickshire NHS Trust. CHESS Book Clinical Skills Workbook 2022–23, section “Cranial Nerve 12 – Hypoglossal Nerve”, pp. 59–60. https://uhmeded.uhcw.nhs.uk/Portals/0/AssetUploads/CHESS%20Book%20Clinical%20Skills%20Workbook%202022-23.pdf?ver=ELcRsPPRSWHk3baBgJ2INQ%3D%3D